In order to detect the presence of a signal in a frequency band, usually an input signal is uniformly sampled in the time domain and converted to the frequency domain. Then the frequency domain spectrum is analyzed for energy peaks indicating the possible presence of a signal. One problem with such an approach is that, at high frequencies, a large number of samples need to be taken in order to overcome aliasing. Such a large number of samples require a large amount of processing and power which tends to stress the receiver.
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